ANALYSTS CfF THE PYROPHYSALITE. 35 



in vapour. The alumine obtained by this process was care- {^^^ 

 fully washed, and heated red hot. In this last operation, 

 when the incandescence was carried to a high degree, the 

 mass emitted fuming vapours; an unexpected phenomenon, 

 that did not take place at a less elevated temperature. As 

 we conceived these vapours to be muriate of ammonia, part 

 of which might have remained in the to ass, it was heated 

 red hot in the fire full two hours longer. After this the alu- Alumine. 

 mine weighed 107*5 grains. In another experiment, when 

 alumine had been exposed to a lower degree of heat, and for 

 a quarter of an hour only, 116 grains were obtained, which 

 were reduced to 107*5 by longer calcination. In these ope- An aluminous 

 rations an aluminous salt was found to attach itself to the 

 edges of the lid that covered the crucible, but the smallness 

 of its quantity did not allow us to examine its nature. Ano- 

 ther time, instead of exposing the alumine to heat, we dis- 

 solved it in sulphuric acid, and added a little potash ; when 

 the result was a crystallization of sulphate of alumine, 

 which continued to the last drop. The sulphuric acid, 

 in dissolving the alumine, left a residuum of 2 grains of si- Silex. 

 lex. 



f. The yellow powder, which was not attacked by the Yellow re'si- 

 caustic potash {c), was dissolved in nitromuriatic acid; being duum - 

 evaporated to dryness, and redissolved in water, a grain and 

 half of silex were separated from it. By adding to the li- Silex. 

 quor succinate of ammonia, a precipitate of oxide of iron, Oxide of iron,, 

 weighing 1*75 grain, was obtained: and on adding caustic 

 ammonia 1 grain of alumine was precipitated^ The re- Alumine, 

 nmining liquor being boiled with carbonate of potash, some 

 carbonate of lime was separated, which, after being heated Lime. x 

 red hot in the fire, weighed 1*75 grain. This portion of 

 lime dissolved in weak sulphuric acid without effervescence 

 forming with it sulphate of liuie. 



Thus, if we subtract the 4 grains of silex gained from the Component 

 mortar in reducing the stone to powder, we find the propor- parts. 

 tions given by 100 parts of it to be 



P2 Al 



umiiie 



